Abstract

The usefulness of surrogates to estimate complex variables describing
community structure, such as the various components of biodiversity, is long established.
Most attention has been given to surrogates of species richness and species diversity and has
focused on identifying a subset of taxa as a surrogate of total community richness or diversity.
In adopting a surrogate measure, it is assumed that the relationship between the surrogate(s)
and total richness or diversity is consistent in both space and time. These assumptions are
rarely examined explicitly. We examined the robustness of potential surrogates of familial
richness and multivariate community structure for macrofauna communities inhabiting
artificial kelp holdfasts by comparing among communities of dissimilar ages and among
communities established at different times of the year. This is important because most benthic
"landscapes" will be a mosaic of patches reflecting different intensities, frequencies, and timing
of disturbances. The total abundance of organisms and familial richness of crustaceans or
polychaetes were all good predictors of total familial richness (R2 . 0.68). In contrast, while
the familial richness of other groups, such as mollusks and echinoderms, were well correlated
with total familial richness for communities at an early stage of development, the strength of
these relationships declined with community age. For multivariate community structure,
carefully selected subsets of ~10% of the total taxa yielded similar patterns to the total suite of
taxa, irrespective of the age of the community. Thus, useful surrogates of both familial
richness and multivariate community structure can be identified for this type of community.
However, the choice of technique for selecting surrogate taxa largely depends on the nature of
the pilot data available, and careful selection is required to ensure that surrogates perform
consistently across different-aged communities. While the specific taxa selected as surrogates
will vary among different communities, and possibly even among similar communities at
different sites, the techniques and the concepts we address are applicable to any community
type.